1. Field of the Invention
This invention relates to a method of forming a print image and a device therefor.
2. Prior Art
Conventionally, an apparatus which involves printing (hereinafter referred to as "the printing apparatus"), such as a personal computer(PC), a word processor, or a label writer, carries out printing of images of letters, figures, symbols, etc. based on print image data formed or produced within itself. Letter data, figure data, and symbol data (hereinafter collectively referred to as "basic image data") defining images of letters, images of figures, and images of symbols, respectively, are stored as font data ready for use in a read only memory (ROM) or a random access memory (RAM) in advance, and read out to be developed into dot matrices of print image data, as needed.
A font is a collection of characters and the like having the same typeface and style, and can be classified according to the method of defining (or manner of expressing) an image of each member thereof into several groups: a font in which the image is defined by numerical formulas or coordinates, such as an outline font in which the shape of the image is defined by a collection of numerical formulas, a vector font in which the shape of the image is expressed by arrangement of segments, and a stroke font in which the shape of the image is expressed by a combination of lines, (hereinafter this group of fonts will be generically referred to as "the outline font", and a bit map font in which the shape of the image is expressed by a uniquely defined bit map (dot pattern). Font data of each member of a font is developed into a dot matrix according to the desired size of a print image, by the use of a font generator in the case of the former font group, while in the case of the bit map font, by expansion of the data through duplicate development of bits, etc. or reduction of the data through thinning of bits, etc. Further, the fonts can be classified according to the typeface. For example, fonts for the Japanese language are classified into Mincho typeface, Gothic typeface, Bold-Mincho typeface, Bold-Gothic typeface, Round-Mincho typeface, Round-Gothic typeface, etc. Font data of such different typefaces is normally stored in the ROM or the like, typeface by typeface, and the printing apparatus is capable of printing images of various typefaces by the use of the ROM installed thereon.
However, according to the conventional print image-forming method and device, to produce data of print images including characters of plurality of typefaces, the printing apparatus is required to be provided with a ROM or the like storing font data of the typefaces, so that if the number of typefaces increases, the cost of component parts increases due to an increase in a required capacity of memory devices such as a ROM. Further, if figures are needed which are slightly different in thickness or roundness of constituent lines from figures originally stored in the RAM or ROM, it is required to newly form the required figures by nonstandard character processing, etc. That is, to use figures slightly different from the original figures available, it not only requires the same labor of the user as needed when a figure is originally formed but also demands a larger capacity of a memory device of the printing apparatus for storing these figures individually.
To overcome these inconveniences, a print image-forming method has been proposed e.g. by Japanese Laid-Open Patent Publication (Kokai) No. 3-173659, which forms a dot pattern by shifting an original dot pattern in a specified direction by a predetermined amount and arranges the resulting dot pattern and the original dot pattern in an overlapping manner to form a letter of thickened typeface (bold-type letter).
However, this method suffers from the inconvenience that the bold-type letter thus obtained is larger in size than the original one, and out of proportion in letter size. It presents a problem particularly in a label printer which is restricted in the width and length of a printable area.